Which alpha-adrenergic blocking agent is used as a reversal for medetomidine?

• A. Yohimbine
• B. Tolazoline
• C. Naloxone
• D. Atipamezole

Answer: (D)

The reversing agent for an alpha-2 agonist like medetomidine must block the same receptors that medetomidine activates, ideally with high selectivity to minimize other effects. Atipamezole fits this role as a selective alpha-2 adrenergic antagonist designed to quickly and effectively counteract medetomidine’s sedative and analgesic actions. By occupying the alpha-2 receptors, it prevents medetomidine from binding, allowing normal sympathetic activity to resume and the patient to wake up sooner with a more predictable recovery.

Yohimbine can block alpha-2 receptors as well, but it is less selective and can provoke more variable cardiovascular responses. Tolazoline is a nonselective alpha-adrenergic antagonist, which can cause broader hemodynamic effects. Naloxone targets opioid receptors and has no mechanism to reverse alpha-2 agonist–induced sedation.